This commit makes the router use the ControlTower to drive the payment
life cycle state machine, to keep track of active payments across
restarts. This lets the router resume payments on startup, such that
their final results can be handled and stored when ready.
This commit changes the format used to store payments within the
DB. Previously this was serialized as one continuous struct
OutgoingPayment, which also contained an Invoice struct we where only
using a few fields of. We now split it up into two simpler sub-structs
CreationInfo, AttemptInfo and PaymentPreimage.
We also want to associate the payments more closely with payment
statuses, so we move to this hierarchy:
There's one top-level bucket "sentPaymentsBucket" which contains a set
of sub-buckets indexed by a payment's payment hash. Each such sub-bucket
contains several fields:
paymentStatusKey -> the payment's status
paymentCreationInfoKey -> the payment's CreationInfo.
paymentAttemptInfoKey -> the payment's AttemptInfo.
paymentSettleInfoKey -> the payment's preimage (or zeroes for
non-settled payments)
The CreationInfo is information that is static during the whole payment
lifcycle. The attempt info is set each time a new payment attempt
(route+paymentID) is sent on the network. The preimage is information
only known when a payment succeeds. It therefore makes sense to split
them.
We keep legacy serialization code for migration puproses.
This commit splits FetchPaymentStatus and
UpdatePaymentStatus, such that they each invoke
helper methods that can be composed into different
db txns. This enables us to improve performance on
send/receive, as we can remove the exclusive lock
from the control tower, and allow concurrent calls
to utilize Batch more effectively.
Fixes#481.
Prior to this commit, payments stored in the channel DB only kept a
record of the payment hash. This is a problem as the preimage is what
serves as proof of payment and a user should be able to look up this
value in the future (not just immediately after payment).
Instead of storing both the payment hash and the preimage, we store the
preimage only since the hash can be derrived from this using a SHA256.
In the RPC listpayments command, we now give the preimage in addition to
the payment hash.
This commit implements an easy optimization by using bolt db’s Batch
method when writing payment details to disk. The AddPaymnent method can
be concurrently called by thousands of grouting due to the way the
payment dispatch pipeline is architected. With this commit, we shave of
a significant amount of running time when users are sending thousands
of payments a second as what would’ve been thousands of writes can now
be coalesced into one or two writes!
This commit modifies the new payment module within the database to
match the coding style of the rest of the package and the project as a
hole. Additionally, a few fields have been renamed, and the extra
timestamp added to the OutgoingPayment struct has been removed as
there’s already a CreationTime field within the Invoice struct that’s
embedded within the OutgoingPayment struct.
Go-fmt files. Refactored code according to the guidelines.
Enhanced payment test: add error checking
and individual context for each API call.
Add Timestamp field to payment struct.
